The present invention relates to shutters for windows, doors or the like in general, and more particularly to improvements in shutters of the type wherein a curtain of lamellae or slats is movable up and down between two upright frame members and the upper end portions of the frame members are adjacent to a rotary main shaft which can be driven in two directions to move the slats up or down. Still more particularly, the invention relates to improvements in shutters of the type wherein the slats can be tilted about substantially horizontal axes to assume partly or fully open or closed positions in partly or fully extended or contracted condition of the curtain.
It is already known to provide a slat lifting, lowering and tilting mechanism with a sleeve which is rotatable in two directions by the manually and/or motorically driven horizontal main shaft (such shaft is mounted at a level above the curtain of slats) and carries or rotates a reel for a tape or band serving to lift the slats when the sleeve rotates in a first direction, and to allow the slats to descend when the sleeve rotates in the opposite direction. The sleeve also transmits motion to a unit which can tilt (i.e., change the inclination of) the slats in order to control the amount of light that can pass between the slats. The arrangement is such that the connection between the sleeve and the tilting unit is terminated or interrupted when the slats assume positions of predetermined or desired inclination with reference to a horizontal or vertical plane. As a rule, the connection includes a clutch which can be disengaged by causing a component part thereof to engage a stop or the like.
A combined slat lifting, tilting and lowering mechanism of the just outlined type is disclosed, for example, in Swiss Pat. No. 608,563. The operation of the patented mechanism is highly reliable; however, its space requirements (especially as considered in the axial direction of the sleeve) are quite pronounced.
A relatively compact slat lifting, lowering and tilting mechanism is disclosed in German Offenlegungsschrift No. 29 00 451 which proposes to install the clutch in the interior of the tilting unit. The clutch is a ratchet-and-pawl clutch whose pawls are movable radially of the ratchet wheel. Mechanisms of the just outlined type are quite complex, sensitive and hard-to-assemble. Moreover, they comprise a relatively large number of parts.